1. Field
The embodiments described below relate generally to radiotherapy treatment. More specifically, some embodiments are directed to determining radiotherapy treatment plan to invoke a biological effect of spatially separated radiation.
2. Description
Radiotherapy or radiation therapy is used to treat cancer and other diseases with ionizing radiation. Conventional radiotherapy systems generate and direct a beam of radiation to a targeted treatment volume within a patient. The radiation beam is intended to injure or destroy cells within the target volume by causing ionizations within the cells or other radiation-induced cell damage.
Radiotherapy treatment plans for delivering radiation to a patient are intended to maximize radiation delivered to a target area, while minimizing the radiation delivered to surrounding healthy tissue. In this regard, a number of different techniques have been developed to address different target areas and types of tumors, as well as radiation exposure concerns. Grid radiotherapy or spatially separated radiotherapy traditionally attaches a grid collimator to the gantry of a radiotherapy device. The grid collimator can produce beneficial biological effects by splitting a radiation beam into a number of smaller beams, shielding portions of a target from being irradiated, and producing a non-uniform irradiation pattern. It has been observed that the biological effects of grid therapy are largely insensitive to changes in dimensions and regularity of the openings in the grid collimator. However, the biological effects of grid radiotherapy may be sensitive to a maximum dose delivered to a volume.
In some instances, a beam shaping device such as a multi-leaf collimator (MLC) may be used to emulate a physical grid collimator, in an effort to achieve the biological benefits of grid radiotherapy but without the need for the physical grid block. However, the emulating of the physical grid collimator constrains prior MLC radiotherapy techniques by simulating the radiation delivery patterns achieved by the conventional physical grids.
The present inventors have realized that conventional grid radiation therapy is limited by physical grid devices, undesired levels of radiation exposure to patients, and other inefficiencies related to emulating patterned grids and MLC grid radiotherapy is also limited due to constraints associated with emulating a physical grid. Accordingly, methods and systems to provide a dynamic delivery of radiation treatment by a radiotherapy system are desired.